Thornton Lake in Granite County: How and When to Fish It

• Overview

  Thornton Lake sits within Granite County in Montana. The surroundings are pine and birch. At about 29 acres, a day is enough to walk the shoreline properly. Roughly 0.9 miles of bank means you can walk to a fresh area when one goes quiet. Anaconda is the closest place, 10 miles off. For a city, Billings is 220 miles off. You are close to a county edge here; who manages the access can change within a short drive.

• Where to Fish on Thornton Lake

  Depth remains unrecorded, so treat the first session as a survey. Look for the band where the shallows give up and the bottom falls away. Read the surface for the wind lane, then fish the edge of it. Public occurrence data for Granite County names rainbow trout, brook trout and brown trout. What holds for the county may not hold for this water. At Thornton Lake light and wind decide more than tackle does.

• Seasonal Patterns

  The seasonal spread runs 18°F to 53°F. The year runs cold to warm and back, with clear transitions. Hard water holds through the cold months, breaking up near mid May. In an average year the thaw lands around mid May and the freeze near mid November. September and October fish steadily right up to the freeze. Plan any trip to Thornton Lake around it.

• Tackle & Baits

  Ownership and access are not documented in what we hold. It formed naturally, so levels move with rainfall rather than with a gate. Nothing in the way of made access shows up nearby: no ramp, no car park, no path. Light line and small metal for the trout; a fly rod earns its place on calm evenings. Sort the permit out before you load the car. Where the way in crosses private ground, ask first. The nearest alternative is Hunters Lake, 0.9 miles out. Confirm before you fish Thornton Lake.